The present invention pertains to processes and apparatus for handling material webs, and more particularly to processes and apparatus for making prefastened garments.
Garments such as disposable absorbent garments have numerous applications including diapers, training pants, feminine care products, and adult incontinence products. The typical disposable absorbent garment is formed as a composite structure including an absorbent assembly disposed between a liquid permeable bodyside liner and a liquid impermeable outer cover. These components can be combined with other materials and features such as elastic materials and containment structures to form a product that is specifically suited to its intended purposes.
Manufacturing techniques for making conventional garments are in some respects inadequate for making new product forms, such as prefastened and refastenable garments. Hence, what is lacking and needed in the art are new processes and apparatus for handling material webs, and in particular in relation to making prefastened garments such as disposable absorbent pants.
In response to the above-referenced unfulfilled need in the art, new processes and apparatus for handling material webs and making prefastened garments have been discovered. One aspect of the present invention pertains to the use of an air knife for material handling. The air knife can be used to position a material for bonding, fastening, or other purposes. The material can comprise any relatively flexible material, whether permeable or impermeable to fluids, such as woven materials, nonwoven materials, films, or the like. The air knife can be used to control and/or guide the position of materials comprising mechanical fastening components which tend to engage other materials which they contact.
Hence, in one embodiment, a method of folding a material includes transporting a material in a machine direction and transporting a panel of the material in operative proximity to an air knife. The air knife comprises a nozzle and a curved Coanda surface. Air is expelled from the nozzle such that the panel is folded over the curved Coanda surface as the material is transported in the machine direction.
Operation of the air knife creates an air sheet formed of the expelled air jet and entrained ambient air. The Coanda surface creates a pressure differential across the two sides of the air sheet, forcing the air sheet to xe2x80x9cattachxe2x80x9d to and follow the Coanda surface. The panel, when transported in operative proximity to the air knife, is drawn to and carried on the air sheet. For purposes of the present application, a material or panel is considered in xe2x80x9coperative proximityxe2x80x9d to an air knife when the material or panel is spaced sufficiently close to the air knife to have its path of travel impacted by operation of the air knife.
In the present methods, the Coanda surface is curved with respect to the nozzle flow direction, and the panel is carried or folded over the curved surface. For purposes of the present invention, a panel or portion of a material being xe2x80x9cfolded over a curved Coanda surfacexe2x80x9d means that the panel is drawn toward the curved surface and wraps over and around the curved surface, supported by the cushion of air flowing over the curved surface. In other words, the panel is inwardly folded about an axis, where the curved Coanda surface is disposed between the axis and the panel. As the material and panel are transported in the machine direction, the panel can be folded from a generally planar position prior to the air knife to a fully folded position further downstream, such that the angle or degree of the fold increases with movement in the machine direction. In particular embodiments, the panel can be folded through an angle of about 45 or greater, and more particularly about 90 degrees or greater. As discussed in greater detail below, the panel can comprise a refastenable fastening component, for example in relation to embodiments concerning refastenable garments.
Another aspect of the invention concerns a method of forming a prefastened pant. One embodiment of such method comprises transporting a stream of discrete, partially assembled and folded pants in a machine direction. Each pant comprises a first waist region with opposed first side panels and a second waist region with opposed second side panels. The method further comprises transporting the first side panels in operative proximity to air knives, which comprise nozzles and curved Coanda surfaces. Air is expelled from the nozzles such that the first side panels are folded over the curved Coanda surfaces. The second side panels are folded into position transversely outward from the first side panels, and the respective first and second side panels are permanently or refastenably bonded together.
Another embodiment of the method of forming a prefastened pant comprises transporting a stream of discrete, partially assembled and folded pants in a machine direction, and transporting the first side panels in operative proximity to air knives. In this embodiment, each pant comprises a first waist region with opposed first side panels including first fastening components, and a second waist region with opposed second side panels including second fastening components. The fastening components are capable of refastenably engaging one another. Each air knife comprises a nozzle and a Coanda surface. Each Coanda surface defines a curved portion and a generally planar portion, where the curved portions are disposed between the nozzles and the generally planar portions. Air is expelled from the nozzles such that the first side panels are folded over the curved Coanda surfaces with the first fastening components disposed on the generally planar portions. The second side panels are moved into overlapping orientation with the first side panels, with the second fastening components positioned transversely outward from the first fastening components. The first and second fastening components are refastenably engaged.
To facilitate high speed formation of the refastenable pants, the air knives can be mounted in a cantilevered configuration, so that the refastenably engaged side panels are transported past the downstream ends of the air knives. In particular embodiments, air is expelled from the nozzles in a direction generally perpendicular to the machine direction. Various techniques can be used to move the second side panels into overlapping orientation with the first side panels. For example, a reciprocating panel folding head can intersect the path of travel of the second side panels. Air knives can also be used to position the second side panels.
A further aspect of the invention concerns an exhausted air knife. In one embodiment, the air knife comprises a plenum defining an internal chamber, a nozzle operatively connected to the internal chamber and defining a nozzle flow direction, and a Coanda surface adjacent and extending beyond the nozzle. The Coanda surface can be curved in cross section relative to the nozzle flow direction and can define a curvature of about 90 degrees or greater from the nozzle to a terminal edge. In this embodiment, the Coanda surface comprises first and second curved portions and first and second generally planar portions, where the first curved portion is disposed between the nozzle and the first generally planar portion and the second curved portion is disposed between the first and second generally planar portions. A flange is positioned in close proximity to the Coanda surface opposite the second generally planar portion and defines therebetween an exhaust passage.
Another embodiment of the exhausted air knife comprises a plenum defining an internal chamber, and a cap attached to the plenum. The cap comprises a first flange, a second flange and an intermediate member connecting the first and second flanges. The first flange is positioned in close proximity to the plenum and defines therebetween a nozzle that is in fluid communication with the internal chamber. The second flange is spaced from the plenum and defines therebetween an exhaust passage. The intermediate member defines at least one aperture in fluid communication with the exhaust passage. A Coanda surface is disposed adjacent and extends beyond the nozzle. The Coanda surface is curved in cross section relative to the nozzle flow direction and defines a curvature of about 90 degrees or greater from the nozzle to a terminal edge.
In particular embodiments, the curvature of the Coanda surface can be about 90 to about 270 degrees, for example about 135 to about 225 degrees. The first and/or second curved portions can in certain embodiments define angles of about 90 degrees or more.
A further aspect of the invention concerns an apparatus for folding a pair of garment side panels. In one embodiment, the apparatus comprises a transport system defining a machine direction and a machine center line, and a pair of air knives located on opposite sides of the machine center line at fixed locations in the machine direction. Each air knife comprises a nozzle and a curved Coanda surface. In this embodiment, each air knife is aligned generally parallel to the machine center line such that the nozzle flow direction is generally perpendicular to the machine direction.
Another aspect of the invention concerns an apparatus for positioning pairs of garment side panels in an overlapping orientation. In one embodiment, the apparatus comprises a transport system defining a machine direction and a machine center line, an interior panel positioning mechanism adapted to fold a first pair of side panels about an axis generally parallel to the machine direction, and an exterior panel positioning mechanism adapted to position a second pair of side panels transversely outward from the first pair of side panels. The interior panel positioning mechanism comprises air knives, with each air knife comprising a nozzle and a curved Coanda surface.
The garments can include refastenable or non-refastenable side seams. Non-refastenable bonded seams can be formed by ultrasonic bonds, adhesive bonds, thermal bonds, sewing, or the like. Fastening components to form refastenable seams can comprise separate elements bonded to another component of the pant. Alternatively, the fastening components can comprise a portion of another element of the pant, such as the bodyside liner, the outer cover, separate side panels if employed, integral side panels if employed, a belt-type component extending transversely across the chassis if employed, or the like. Thus, unless otherwise specified, the term xe2x80x9cfastening componentxe2x80x9d includes separate components which function as fasteners and regions of materials such as side panels, liners, outer covers or the like which function as fasteners. Moreover, a single material can define multiple fastening components to the extent that different regions of the material function as separate fasteners. The fastening components can be located on the side panels, between the side panels such as on the absorbent chassis, or a combination of the two. The fastening components can have any desired shape, such as square, rectangular, round, curved, oval, irregularly shaped, or the like. Each fastening component can comprise a single fastening element or multiple fastening elements.
The fastening components can comprise any refastenable fasteners suitable for absorbent articles, such as adhesive fasteners, cohesive fasteners, mechanical fasteners, or the like. In particular embodiments the fastening components comprise mechanical fastening elements for improved performance. Suitable mechanical fastening elements can be provided by interlocking geometric shaped materials, such as hooks, loops, bulbs, mushrooms, arrowheads, balls on stems, male and female mating components, buckles, snaps, or the like. In particular embodiments, the fastening components and mating fastening components comprise hook-and-loop fastening elements. One skilled in the art will recognize that the shape, density and polymer composition of the hooks and loops may be selected to obtain the desired level of securement between the fastening components and the mating fastening components. A more aggressive hook material may comprise a material with a greater average hook height, a greater percentage of directionally-aligned hooks, or a more aggressive hook shape.
Refastenable fastening systems allow for easy inspection of the interior of the pant-like product. If necessary, the fastening system also allows the pant to be removed quickly and easily. This is particularly beneficial when the pant contains messy excrement. For training pants, the caregiver can completely remove the pant-like product and replace it with a new one without having to remove the child""s shoes and clothing.
The present invention can be used in the manufacture of a wide variety of absorbent and non-absorbent products, including training pants, swim pants, diaper pants, incontinence garments, feminine care products, health care garments, apparel for institutional, industrial and consumer use, or other garments. Absorbent articles are adapted to be worn adjacent to the body of a wearer to absorb and contain various exudates discharged from the body. The absorbent articles can be prefastened to provide a pant-like product for the user. The product can then be pulled on like a conventional training pant, and subsequently checked or removed with the ease of a diaper-like product. Moreover, the product may be applied like a diaper rather than like a pant. Supplemental releasable fastening means such as frangible point bonds may be employed to maintain the absorbent article in a pant configuration until the user intentionally disengages the fasteners.
Particular training pants suitable for use with the present invention are disclosed in U.S. patent application Ser. No. 09/444,083, filed on Nov. 22, 1999 (corresponding to PCT application WO 00/37009 published Jun. 29, 2000) by A. Fletcher et al. and titled xe2x80x9cAbsorbent Articles With Refastenable Side Seams;xe2x80x9d which is incorporated herein by reference. This reference describes various materials and methods for constructing training pants. Training pants can also be constructed using the methods and apparatus disclosed in U.S. Pat. No. 4,940,464 issued Jul. 10, 1990 to Van Gompel et al.; and U.S. Pat. No. 5,766,389 issued Jun. 16, 1998 to Brandon et al.; which are also incorporated herein by reference.
Within the context of this specification, each term or phrase below will include the following meaning or meanings.
xe2x80x9cBondedxe2x80x9d refers to the joining, adhering, connecting, attaching, or the like, of two elements. Two elements will be considered to be bonded together when they are bonded directly to one another or indirectly to one another, such as when each is directly bonded to intermediate elements.
xe2x80x9cComprisingxe2x80x9d is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.
xe2x80x9cConnectedxe2x80x9d refers to the joining, adhering, bonding, attaching, or the like, of two elements. Two elements will be considered to be connected together when they are connected directly to one another or indirectly to one another, such as when each is directly connected to intermediate elements.
xe2x80x9cDisposablexe2x80x9d refers to articles which are designed to be discarded after a limited use rather than being laundered or otherwise restored for reuse.
xe2x80x9cDisposed,xe2x80x9d xe2x80x9cdisposed on,xe2x80x9d and variations thereof are intended to mean that one element can be integral with another element, or that one element can be a separate structure bonded to or placed with or placed near another element.
xe2x80x9cElastic,xe2x80x9d xe2x80x9celasticizedxe2x80x9d and xe2x80x9celasticityxe2x80x9d mean that property of a material or composite by virtue of which it tends to recover its original size and shape after removal of a force causing a deformation.
xe2x80x9cElastomericxe2x80x9d refers to a material or composite which can be elongated by at least 25 percent of its relaxed length and which will recover, upon release of the applied force, at least 10 percent of its elongation. It is generally preferred that the elastomeric material or composite be capable of being elongated by at least 100 percent, more preferably by at least 300 percent, of its relaxed length and recover, upon release of an applied force, at least 50 percent of its elongation.
xe2x80x9cFabricsxe2x80x9d is used to refer to all of the woven, knitted and nonwoven fibrous webs. xe2x80x9cFlexiblexe2x80x9d refers to materials which are compliant and which will readily conform to the general shape and contours of the wearer""s body.
xe2x80x9cForcexe2x80x9d includes a physical influence exerted by one body on another which produces acceleration of bodies that are free to move and deformation of bodies that are not free to move. Force is expressed in grams per unit area.
xe2x80x9cGraphicxe2x80x9d refers to any design, pattern, or the like that is visible on an absorbent article.
xe2x80x9cHydrophilicxe2x80x9d describes fibers or the surfaces of fibers which are wetted by the aqueous liquids in contact with the fibers. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials or blends of fiber materials can be provided by a Cahn SFA-222 Surface Force Analyzer System, or a substantially equivalent system. When measured with this system, fibers having contact angles less than 90xc2x0 are designated xe2x80x9cwettablexe2x80x9d or hydrophilic, while fibers having contact angles greater than 90xc2x0 are designated xe2x80x9cnonwettablexe2x80x9d or hydrophobic.
xe2x80x9cIntegralxe2x80x9d is used to refer to various portions of a single unitary element rather than separate structures bonded to or placed with or placed near one another.
xe2x80x9cInwardxe2x80x9d and xe2x80x9coutwardxe2x80x9d refer to positions relative to the center of an absorbent article, and particularly transversely and/or longitudinally closer to or away from the longitudinal and transverse center of the absorbent article.
xe2x80x9cLayerxe2x80x9d when used in the singular can have the dual meaning of a single element or a plurality of elements.
xe2x80x9cLiquid impermeablexe2x80x9d, when used in describing a layer or multi-layer laminate, means that a liquid, such as urine, will not pass through the layer or laminate, under ordinary use conditions, in a direction generally perpendicular to the plane of the layer or laminate at the point of liquid contact. Liquid, or urine, may spread or be transported parallel to the plane of the liquid impermeable layer or laminate, but this is not considered to be within the meaning of xe2x80x9cliquid impermeablexe2x80x9d when used herein.
xe2x80x9cLongitudinalxe2x80x9d and xe2x80x9ctransversexe2x80x9d have their customary meaning. The longitudinal axis lies in the plane of the article and is generally parallel to a vertical plane that bisects a standing wearer into left and right body halves when the article is worn. The transverse axis lies in the plane of the article generally perpendicular to the longitudinal axis. The article as illustrated is longer in the longitudinal direction than in the transverse direction.
xe2x80x9cMemberxe2x80x9d when used in the singular can have the dual meaning of a single element or a plurality of elements.
xe2x80x9cNonwovenxe2x80x9d and xe2x80x9cnonwoven webxe2x80x9d refer to materials and webs of material which are formed without the aid of a textile weaving or knitting process.
xe2x80x9cOperatively joined,xe2x80x9d with reference to the attachment of an elastic member to another element, means that the elastic member when attached to or connected to the element, or treated with heat or chemicals, by stretching, or the like, gives the element elastic properties; and with reference to the attachment of a non-elastic member to another element, means that the member and element can be attached in any suitable manner that permits or allows them to perform the intended or described function of the joinder. The joining, attaching, connecting or the like can be either directly, such as joining either member directly to an element, or can be indirectly by means of another member disposed between the first member and the first element.
xe2x80x9cOuter cover graphicxe2x80x9d refers to a graphic that is directly visible upon inspection of the exterior surface of a garment, and for a refastenable garment is in reference to inspection of the exterior surface of the garment when the fastening system is engaged as it would be during use.
xe2x80x9cPermanently bondedxe2x80x9d refers to the joining, adhering, connecting, attaching, or the like, of two elements of an absorbent garment such that the elements tend to be and remain bonded during normal use conditions of the absorbent garment.
xe2x80x9cRefastenablexe2x80x9d refers to the property of two elements being capable of releasable attachment, separation, and subsequent releasable reattachment without substantial permanent deformation or rupture.
xe2x80x9cReleasably attached,xe2x80x9d xe2x80x9creleasably engagedxe2x80x9d and variations thereof refer to two elements being connected or connectable such that the elements tend to remain connected absent a separation force applied to one or both of the elements, and the elements being capable of separation without substantial permanent deformation or rupture. The required separation force is typically beyond that encountered while wearing the absorbent garment.
xe2x80x9cRupturexe2x80x9d means the breaking or tearing apart of a material; in tensile testing, the term refers to the total separation of a material into two parts either all at once or in stages, or the development of a hole in some materials.
xe2x80x9cStretch bondedxe2x80x9d refers to an elastic member being bonded to another member while the elastic member is extended at least about 25 percent of its relaxed length. Desirably, the term xe2x80x9cstretch bondedxe2x80x9d refers to the situation wherein the elastic member is extended at least about 100 percent, and more desirably at least about 300 percent, of its relaxed length when it is bonded to the other member.
xe2x80x9cStretch bonded laminatexe2x80x9d refers to a composite material having at least two layers in which one layer is a gatherable layer and the other layer is an elastic layer. The layers are joined together when the elastic layer is in an extended condition so that upon relaxing the layers, the gatherable layer is gathered.
xe2x80x9cSurfacexe2x80x9d includes any layer, film, woven, nonwoven, laminate, composite, or the like, whether pervious or impervious to air, gas, and/or liquids.
xe2x80x9cTensionxe2x80x9d includes a uniaxial force tending to cause the extension of a body or the balancing force within that body resisting the extension.
xe2x80x9cThermoplasticxe2x80x9d describes a material that softens when exposed to heat and which substantially returns to a nonsoftened condition when cooled to room temperature.
These terms may be defined with additional language in the remaining portions of the specification.